1. Field of the Invention
The present invention relates to optical devices which include an adjustable optical element which may be adjusted with high precision, and in particular to such optical devices which are adjustable about two perpendicular axes and are vibration and temperature stable.
2. Description of the Related Art
Adjustable optical devices may be used in relay optics systems which divide and coregister multiple optical beams. In some cases, such systems must be accommodated in an apparatus having limited package space, for instance, a satellite. A relay optics system for a satellite is described in U.S. Pat. No. 4,801,202, entitled xe2x80x9cMethod and Apparatus For Radiometer Star Sensingxe2x80x9d, the disclosure of which is expressly incorporated herein by reference. This patent describes an earth scanning radiometer instrument which uses a mirror to collect radiation, and transfers an image of the radiation onto the surface of a detector which converts the incident radiation into an electrical signal, which is then converted into a digital image. To provide images across a broad spectrum of radiation the collected radiation is divided and directed onto several detector surfaces sensitive to discrete wavelengths. Such division is referred to in the art as relay optics. It is to be understood that, in the context of the following discussion, the term xe2x80x9copticalxe2x80x9d does not relate solely to the visible light spectrum; rather, the term relates to radiation across a broad band of wavelengths, including those on which visible light is transmitted.
Proper digital imaging requires that the divided detectors be aligned with one another, i.e., coregistered. Relay optics systems require physical space and contribute mass to the structure on which they are installed. In particular, where that structure is a satellite, the shortcomings of previous relay optics systems are, in part, associated with their package requirements and weight. Further, accessibility to the optical elements which comprise the system, once installed, is often difficult. The mechanical motions associated with adjustment of the optical elements are very fine, and the movements associated therewith must be free of backlash. In previous relay optics systems, complex mechanical mechanisms are necessary to facilitate adjustment of the divided beams onto the coregistered detectors. Moreover, the elements must not move after being properly adjusted, and certainly not after launch of the satellite. Further, the adjustment mechanism is subjected to substantial vibration, particularly during launch, and once in orbit is subjected to temperatures which may vary in a range from aboutxe2x88x9220xc2x0 C. to about 70xc2x0 C. The vibratory inputs and temperature variations to which previous adjustment mechanism are subjected may affect proper adjustment of the optical element.
Moreover, the adjustment mechanism itself may contribute significantly to the relay optics system, and thus to the weight of, and the package space which must be accommodated by, the satellite. Further, some earth-bound communication systems may have limited package space in which a relay optics system must be accommodated.
Means for providing an improved, easily yet finely adjustable optical device and associated adjustment mechanism for a relay optics system, which is small in size, lightweight, vibration and temperature stable, and capable of high-resolution adjustment to produce a coregistered image is highly desirable, particularly for use in satellite-based and some earth-bound relay optics systems.
The present invention provides a lightweight, precisely adjustable optical device which may be used in a relay optics system which divides and coregisters multiple optical beams and includes a flexure mechanism to produce high-resolution adjusting movements of the optical element. The device is lightweight and occupies limited volume, making it suitable for spaceflight use. The device provides means for locking the adjusted optical element into place, thereby providing vibration stability, and is comprised of materials having common coefficients of thermal expansion, thereby providing thermal stability.
In one embodiment, the movement between the housing, to which the optical element is mounted, and the base portion, which is attached to the satellite chassis, is substantially frictionless.
In another embodiment, the adjusting device is separable from the optical device, the latter of which is attached to the satellite chassis; the optical element is locked in position after adjustment. The adjusting device is disengaged from the optical device after locking the optical element in position, and does not fly with the satellite.
The present invention provides an adjustable optical device including an optical element, a housing having an adjusting post fixed thereto, the optical element mounted to the housing, the housing adjusting post having a plane of movement, and an adjustment mechanism. The housing is flexibly connected to the adjustment mechanism, which includes a moving adjusting member in sliding engagement with the housing adjusting post. One of the adjusting member and the housing adjusting post includes a wedge, and the housing adjusting post is urged into movement in its plane of movement in response to relative movement between the adjusting member and the adjusting post, whereby the orientation of the optical element relative to the adjusting mechanism is adjusted by movement of the moving adjusting member.
The present invention also provides an adjustable optical device including a housing having a substantially spherical outer surface, an optical element disposed within the housing, a base having a substantially spherical inner surface, the base inner surface overlying a portion of the housing outer surface, the base inner surface and the housing outer surface frictionally engaged, and a cover having a substantially spherical inner surface, the cover inner surface overlying a portion of the housing outer surface, the cover inner surface and the housing outer surface frictionally engaged. The housing is disposed between the base and the cover, and the cover is attached to the base. Frictional engagement between the base and the housing, and the cover and the housing, has a first level and a second level. The first level is substantially less than the second level, whereby relative movement between the housing and the base is resisted yet permitted at the first frictional engagement level. Relative movement between the housing and the base is prevented at the second frictional engagement level.
The present invention also provides an adjustable optical device including an optical element and a housing, the optical element disposed within the housing. Also included is a base having a substantially spherical inner surface. The housing has a substantially spherical outer surface engaged with the base substantially spherical inner surface. The housing is provided with a driven surface, and has a tilt axis and a roll axis about which the orientation of the housing relative to the base is adjusted. An adjustment device has an operating position relative to the base, and includes a moving adjusting mechanism which includes a driving surface, the driven and driving surfaces engaged in the operating position. The adjusting mechanism includes a lever operatively connected to the driving surface, the lever having two substantially perpendicular degrees of movement. Movement of the housing about one of its tilt and roll axes is in response to movement of the lever along one of its degrees of movement.
The present invention further provides an adjustable optical device including an optical element, a base, and a housing, the optical element mounted in the housing. The housing is coupled to the base and has at least one degree of movement relative to the base, whereby the orientation of the optical element relative to the base is adjusted by the movement of the housing in the at least one degree of movement. Also included is an adjustment device detachably connected to the base and having a moving adjusting mechanism. When the adjustment device is connected to the base, the adjusting mechanism is operatively connected to the housing to move the housing in its at least one degree of movement in response to movement of the adjusting mechanism. The housing is selectively locked to the base and remains selectively locked to the base when the adjustment device is detached from the base.
The present invention also provides an adjustable optical device including a housing having a spherical outer surface, the housing outer surface having a radius of curvature, an optical element mounted within the housing, a base having a spherical inner surface, the base inner surface having substantially the same radius of curvature as the housing outer surface, and a cover having a spherical inner surface, the cover inner surface having substantially the same radius of curvature as the housing outer surface. The cover and the base inner surfaces are in frictional engagement with the housing outer surface and are moveable relative to each other to thereby selectively frictionally clamp the housing against movement relative to the base and the cover.